| Microvalves are an essential part of microfluidic systems for chemical and biological analysis. However, the lack of high performance materials has hindered the development of microactuators capable of driving valves with combined rapid response and high closing forces. Paraffin-based phase change microvalves achieve high open/close flow ratios and closing pressures, which minimize leakage. In addition, they are stable and easy to fabricate. However, these valves are intrinsically slow, due to the low thermal conductivity of paraffin coupled to its high specific heat capacity. We report on a rapid response phase change microactuator for microvalve applications based on a polymer membrane and a novel composite of paraffin and high thermal conductivity nanoparticles. By modifying the thermal properties of paraffin, faster heat transfer and actuation speed can be achieved. This design can be used to fabricate microvalves in contamination-sensitive lab-on-chip (LOC) systems where low leakage and high speed flow control are required. |
